The key can be obtained by:
- Sleeping with Slim (female Chosen One only).
- Stealing the key from him.
- Killing him and taking it.
- Convincing Slim to give it to the Chosen One.
- Feeding the yellow dog in Klamath Downtown a piece of meat jerky (he'll cough it up and follow the Chosen One around).
- Clicking "barter", then trading for the key (it has a value of 0, so he'll accept even $1).